Flexural behavior of steel-concrete composite beams with U-shaped steel girders

[EN] This paper focuses on a new type of steel-concrete composite beams consisting of U-shaped steel girders and angle connectors. Compared with conventional composite beams consisting of wide flange girders and headed stud connectors (or short channel connectors), the composite beams considered in this study have favorable flexural performance while reducing the excessive costs and potential construction challenges due to installation of the stud and/or channel shear connectors. Through four-point bending tests on five specimens, this research team experimentally investigated flexural behavior of such new composite beams. The five specimens were varied to have different angle connector intervals and installation locations. Test results showed that composite beams with angle connectors welded to the webs of U-shaped steel girder failed in brittle failure modes while composite beams with angle connectors welded on the top flange of U-shaped steel girder failed in ductile failure mode. Moreover, finite element analysis were performed and the results were verified by the experimental results. According to the parametric analysis results, concrete strength has little effect on flexural behavior of composite beams while increasing yield stress of steel girder could significantly increase the flexural resistance but could not change the initial stiffness. Increasing the height of steel girder, the thickness and width of bottom flange are recommended to improve the flexural behavior of composite beams.This research was financially supported by the Jilin Provincial Science & Technology Development Project Agreement (20180201031SF) and the National Natural Science Foundation of China under Awards No. 51578187.Liu, Y.; Guo, L.; Li, Z. (2018). Flexural behavior of steel-concrete composite beams with U-shaped steel girders. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 161-167. https://doi.org/10.4995/ASCCS2018.2018.7922OCS16116

Genetic diversity of five goat breeds in China based on microsatellite markers

The genetic diversity of five goat breeds in China was surveyed using 15 microsatellites. The five goat breeds included Tangshan dairy goat (TSD), Liaoning cashmere goat (LNC), Nanjiang yellow goat (NJY), Chengde  polled goat (CDP) and Leizhou black goat (LZB). The mean polymorphism information content value (PIC) of  the populations ranged from 0.6606 to 0.8405. The mean heterozygosity (H) of the populations ranged from  0.7936 to 0.8202. The mean number of effective allele (Ne) of the populations ranged from 5.3373 to 5.8812 and the coefficient of genetic differentiation between breeds was 0.0620. It was suggested that the five goat  populations have abundant genetic diversity and extensive genetic basis, with limited inbreeding, especially in Leizhou black goat. The unweighted pair-group method with arithmetic averages (UPGMA) dendrogram based  on the Nei's standard genetic distance indicated that Tangshan dairy goat, Chengde polled goat and Liaoning  cashmere goat breeds / populations clustered together. The Nanjiang yellow goat and Leizhou black goat  populations clustered together, consistent with the geographical distribution of goat breeds.Key words: Goat, microsatellite, genetic diversity, clustering

Application of a Force Sensor in Wire Bonding Process

Wire bonder is important equipment in semiconductor end-package. The benefits of using force sensor are precisely force control and earlier contact detection. In this paper, we introduced an application of a force sensor in the wire bonding process. We proposed the control strategy of the whole bonding process with the force sensor. In the bonding process, it's very important to make sure the safety before switching between the force control and position control. A contact detection method in force mode was introduced to get a smooth switch from position control to force control. Before switching from the force control to position control, a two-steps method was proposed to prevent vibrations. The experiments results show that a good bonding performance was achieved by applying with the force sensor

Application of a Force Sensor in Wire Bonding Process

Abstract: Wire bonder is important equipment in semiconductor end-package. The benefits of using force sensor are precisely force control and earlier contact detection. In this paper, we introduced an application of a force sensor in the wire bonding process. We proposed the control strategy of the whole bonding process with the force sensor. In the bonding process, it's very important to make sure the safety before switching between the force control and position control. A contact detection method in force mode was introduced to get a smooth switch from position control to force control. Before switching from the force control to position control, a twosteps method was proposed to prevent vibrations. The experiments results show that a good bonding performance was achieved by applying with the force sensor

Study on collapse mechanism of steel frame with CFST-columns under column-removal scenario

The design of structure against progressive collapse has tended towards more quantitative design where utilizing catenary action becomes essential. In this paper, a single internal column removal test was conducted for a 1/3 scale 4-bay steel frame with concrete-filled steel tubular (CFST) columns. The anti-collapse mechanism of the frame under the scenario of column loss is discussed. Both FE model and simplified analytical model are developed to investigate the behavior of steel frame with CFST columns in resisting progressive collapse. The accuracy of the two models is verified through the experimental results. The anti-collapse measures of the proposed model are sensitive to the modeling techniques used to simulate the CFST columns. A method based on the energy equivalence is used to evaluate the dynamic behavior of the frame. The results show that the DAF (dynamic amplification factor) value of 2.0 which is recommended by DoD provision in linear static analysis is reasonable. However the mobilization of “catenary action” which is not considered in DoD provision would increase the DAF value as currently given in DoD

Analysis of Agricultural Land Use Change in the Middle Reach of the Heihe River Basin, Northwest China

The Heihe River Basin (HRB) is the second largest inland river basin in arid Northwest China. The expanding agricultural irrigation, growing industrialization, and increasing urban development in the middle reach have depleted much of the river flow to the lower reach, degrading the corresponding ecosystems. Since the enactment of the State Council of China’s new HRB water allocation policy in 2000 tremendous land use and land cover (LULC) changes have taken place to reduce water consumption in the middle reach and deliver more water downstream. This paper analyzes LULC changes during the period of 2000–2009 to understand how the changing land use patterns have altered water resource dynamics in the region. Results, while yet to be further verified in the field, show that from 2000 to 2009, urban, agricultural land, rangeland, and forest areas have increased, and barren area has decreased. Within the cropland, rice (a high water consumption crop) planting area decreased, while corn and wheat (relatively lower water consumption crops) planting areas increased. These changes in land use patterns, especially in the agricultural zones, have ensured the discharge of the required amount of water to the lower reach

High Speed Motion Control System With Predictive Observer and Its Parameters Optimization

The traditional control of high speed motion control system usually employs feedforward control to provide phase advance. In this paper, we proposed a predictive observer to compensate phase lags in the feedback loop. By employing the observer, the velocity and the position controller can be designed as for a plant does not have phase lag elements. Then, loop gains can be enlarged and motion speed can be improved. There are two sets of parameters need to be set, the controller’s and the observer’s. We applied least square algorithm for model estimation and simplex method for controller auto tuning. The algorithms were tested in simulations. The results show that the motion performance is extremely improved by the predictive observer. The accuracy of the estimated model has errors less than 2.5%. The preferred motion performance can be got according to the auto-tuned control parameters which implies that the strategy for parameters setting works well

Photon penetration depth in human brain for light stimulation and treatment: A realistic Monte Carlo simulation study

Light has been clinically utilized as a stimulation in medical treatment, such as Low-level laser therapy and photodynamic therapy, which has been more and more widely accepted in public. The penetration depth of the treatment light is important for precision treatment and safety control. The issue of light penetration has been highlighted in biomedical optics field for decades. However, quantitative research is sparse and even there are conflicts of view on the capability of near-infrared light penetration into brain tissue. This study attempts to quantitatively revisit this issue by innovative high-realistic 3D Monte Carlo modeling of stimulated light penetration within high-precision Visible Chinese human head. The properties of light, such as its wavelength, illumination profile and size are concern in this study. We made straightforward and quantitative comparisons among the effects by the light properties (i.e., wavelengths: 660, 810 and 980nm; beam types: Gaussian and flat beam; beam diameters: 0, 2, 4 and 6cm) which are in the range of light treatment. The findings include about 3% of light dosage within brain tissue; the combination of Gaussian beam and 810nm light make the maximum light penetration (>5cm), which allows light to cross through gray matter into white mater. This study offered us, the first time as we know, quantitative guide for light stimulation parameter optimization in medical treatment